Computational approaches to the study of some lanthanide (III) - Polyazamacrocyclic chelates for magnetic resonance imaging

A set of parameters consistent with the CHARMM force field has been determi ned for molecular dynamics simulations of several DOTA- and DOTP-Ln(III) ch elates. Bonding and van der Waals parameters were derived from the availabl e experimental data and analogy to similar ones in the existing force field . Net atomic charges were derived from ab initio calculations at the Hartre e-Fock level to reproduce molecular electrostatic potentials (ESPs), with a n effective core potential (ECP) basis set for the metal ion and the 6-31G* basis set for the ligand atoms. The charges are consistent with the TIP3P water model. Preliminary molecular dynamics simulations of the lanthanide c helates in aqueous solution were performed using the Nose-Hoover thermostat at 300 K. The new parameters correctly predicted the molecular structures and stability of the chelates major and minor isomers. (C) 1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 237-248, 1999.